src/bin/lttng-sessiond/syscall.c

   1 /*
   2  * Copyright (C) 2014 - David Goulet <dgoulet@efficios.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License, version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program; if not, write to the Free Software Foundation, Inc., 51
  15  * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #define _GNU_SOURCE
  19 #define _LGPL_SOURCE
  20 #include <common/bitfield.h>
  21 #include <common/common.h>
  22 #include <common/kernel-ctl/kernel-ctl.h>
  23
  24 #include "lttng-sessiond.h"
  25 #include "kernel.h"
  26 #include "syscall.h"
  27 #include "utils.h"
  28
  29 /* Global syscall table. */
  30 struct syscall *syscall_table;
  31
  32 /* Number of entry in the syscall table. */
  33 static size_t syscall_table_nb_entry;
  34
  35 /*
  36  * Populate the system call table using the kernel tracer.
  37  *
  38  * Return 0 on success and the syscall table is allocated. On error, a negative
  39  * value is returned.
  40  */
  41 int syscall_init_table(void)
  42 {
  43         int ret, fd, err;
  44         size_t nbmem;
  45         FILE *fp;
  46         /* Syscall data from the kernel. */
  47         size_t index;
  48         uint32_t bitness;
  49         char name[SYSCALL_NAME_LEN];
  50
  51         DBG3("Syscall init system call table");
  52
  53         fd = kernctl_syscall_list(kernel_tracer_fd);
  54         if (fd < 0) {
  55                 ret = -errno;
  56                 PERROR("kernelctl syscall list");
  57                 goto error_ioctl;
  58         }
  59
  60         fp = fdopen(fd, "r");
  61         if (!fp) {
  62                 ret = -errno;
  63                 PERROR("syscall list fdopen");
  64                 goto error_fp;
  65         }
  66
  67         nbmem = SYSCALL_TABLE_INIT_SIZE;
  68         syscall_table = zmalloc(sizeof(struct syscall) * nbmem);
  69         if (!syscall_table) {
  70                 ret = -errno;
  71                 PERROR("syscall list zmalloc");
  72                 goto error;
  73         }
  74
  75         while (fscanf(fp,
  76                                 "syscall { index = %zu; \
  77                                 name = %" XSTR(SYSCALL_NAME_LEN) "[^;]; \
  78                                 bitness = %u; };\n",
  79                                 &index, name, &bitness) == 3) {
  80                 if (index >= nbmem ) {
  81                         struct syscall *new_list;
  82                         size_t new_nbmem;
  83
  84                         /* Double memory size. */
  85                         new_nbmem = max(index, nbmem << 1);
  86                         if (new_nbmem < nbmem) {
  87                                 /* Overflow, stop everything, something went really wrong. */
  88                                 ERR("Syscall listing memory size overflow. Stopping");
  89                                 free(syscall_table);
  90                                 syscall_table = NULL;
  91                                 ret = -EINVAL;
  92                                 goto error;
  93                         }
  94
  95                         DBG("Reallocating syscall table from %zu to %zu entries", nbmem,
  96                                         new_nbmem);
  97                         new_list = realloc(syscall_table, new_nbmem * sizeof(*new_list));
  98                         if (!new_list) {
  99                                 ret = -errno;
 100                                 PERROR("syscall list realloc");
 101                                 goto error;
 102                         }
 103
 104                         /* Zero out the new memory. */
 105                         memset(new_list + nbmem, 0,
 106                                         (new_nbmem - nbmem) * sizeof(*new_list));
 107                         nbmem = new_nbmem;
 108                         syscall_table = new_list;
 109                 }
 110                 syscall_table[index].index = index;
 111                 syscall_table[index].bitness = bitness;
 112                 if (lttng_strncpy(syscall_table[index].name, name,
 113                                 sizeof(syscall_table[index].name))) {
 114                         ret = -EINVAL;
 115                         free(syscall_table);
 116                         syscall_table = NULL;
 117                         goto error;
 118                 }
 119                 /*
 120                 DBG("Syscall name '%s' at index %" PRIu32 " of bitness %u",
 121                                 syscall_table[index].name,
 122                                 syscall_table[index].index,
 123                                 syscall_table[index].bitness);
 124                 */
 125         }
 126
 127         syscall_table_nb_entry = index;
 128
 129         ret = 0;
 130
 131 error:
 132         err = fclose(fp);
 133         if (err) {
 134                 PERROR("syscall list fclose");
 135         }
 136         return ret;
 137
 138 error_fp:
 139         err = close(fd);
 140         if (err) {
 141                 PERROR("syscall list close");
 142         }
 143
 144 error_ioctl:
 145         return ret;
 146 }
 147
 148 /*
 149  * Helper function for the list syscalls command that empty the temporary
 150  * syscall hashtable used to track duplicate between 32 and 64 bit arch.
 151  *
 152  * This empty the hash table and destroys it after. After this, the pointer is
 153  * unsuable. RCU read side lock MUST be acquired before calling this.
 154  */
 155 static void destroy_syscall_ht(struct lttng_ht *ht)
 156 {
 157         struct lttng_ht_iter iter;
 158         struct syscall *ksyscall;
 159
 160         DBG3("Destroying syscall hash table.");
 161
 162         if (!ht) {
 163                 return;
 164         }
 165
 166         cds_lfht_for_each_entry(ht->ht, &iter.iter, ksyscall, node.node) {
 167                 int ret;
 168
 169                 ret = lttng_ht_del(ht, &iter);
 170                 assert(!ret);
 171                 free(ksyscall);
 172         }
 173         ht_cleanup_push(ht);
 174 }
 175
 176 /*
 177  * Allocate the given hashtable pointer.
 178  *
 179  * Return 0 on success else a negative LTTNG error value.
 180  */
 181 static int init_syscall_ht(struct lttng_ht **ht)
 182 {
 183         int ret;
 184
 185         *ht = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 186         if (!*ht) {
 187                 ret = -LTTNG_ERR_NOMEM;
 188         } else {
 189                 ret = 0;
 190         }
 191
 192         return ret;
 193 }
 194
 195 /*
 196  * Lookup a syscall in the given hash table by name.
 197  *
 198  * Return syscall object if found or else NULL.
 199  */
 200 static struct syscall *lookup_syscall(struct lttng_ht *ht, const char *name)
 201 {
 202         struct lttng_ht_node_str *node;
 203         struct lttng_ht_iter iter;
 204         struct syscall *ksyscall = NULL;
 205
 206         assert(ht);
 207         assert(name);
 208
 209         lttng_ht_lookup(ht, (void *) name, &iter);
 210         node = lttng_ht_iter_get_node_str(&iter);
 211         if (node) {
 212                 ksyscall = caa_container_of(node, struct syscall, node);
 213         }
 214
 215         return ksyscall;
 216 }
 217
 218 /*
 219  * Using the given syscall object in the events array with the bitness of the
 220  * syscall at index in the syscall table.
 221  */
 222 static void update_event_syscall_bitness(struct lttng_event *events,
 223                 unsigned int index, unsigned int syscall_index)
 224 {
 225         assert(events);
 226
 227         if (syscall_table[index].bitness == 32) {
 228                 events[syscall_index].flags |= LTTNG_EVENT_FLAG_SYSCALL_32;
 229         } else {
 230                 events[syscall_index].flags |= LTTNG_EVENT_FLAG_SYSCALL_64;
 231         }
 232 }
 233
 234 /*
 235  * Allocate and initialize syscall object and add it to the given hashtable.
 236  *
 237  * Return 0 on success else -LTTNG_ERR_NOMEM.
 238  */
 239 static int add_syscall_to_ht(struct lttng_ht *ht, unsigned int index,
 240                 unsigned int syscall_index)
 241 {
 242         int ret;
 243         struct syscall *ksyscall;
 244
 245         assert(ht);
 246
 247         ksyscall = zmalloc(sizeof(*ksyscall));
 248         if (!ksyscall) {
 249                 ret = -LTTNG_ERR_NOMEM;
 250                 goto error;
 251         }
 252
 253         strncpy(ksyscall->name, syscall_table[index].name,
 254                         sizeof(ksyscall->name));
 255         ksyscall->bitness = syscall_table[index].bitness;
 256         ksyscall->index = syscall_index;
 257         lttng_ht_node_init_str(&ksyscall->node, ksyscall->name);
 258         lttng_ht_add_unique_str(ht, &ksyscall->node);
 259         ret = 0;
 260
 261 error:
 262         return ret;
 263 }
 264
 265 /*
 266  * List syscalls present in the kernel syscall global array, allocate and
 267  * populate the events structure with them. Skip the empty syscall name.
 268  *
 269  * Return the number of entries in the array else a negative value.
 270  */
 271 ssize_t syscall_table_list(struct lttng_event **_events)
 272 {
 273         int i, index = 0;
 274         ssize_t ret;
 275         struct lttng_event *events;
 276         /* Hash table used to filter duplicate out. */
 277         struct lttng_ht *syscalls_ht = NULL;
 278
 279         assert(_events);
 280
 281         DBG("Syscall table listing.");
 282
 283         rcu_read_lock();
 284
 285         /*
 286          * Allocate at least the number of total syscall we have even if some of
 287          * them might not be valid. The count below will make sure to return the
 288          * right size of the events array.
 289          */
 290         events = zmalloc(syscall_table_nb_entry * sizeof(*events));
 291         if (!events) {
 292                 PERROR("syscall table list zmalloc");
 293                 ret = -LTTNG_ERR_NOMEM;
 294                 goto error;
 295         }
 296
 297         ret = init_syscall_ht(&syscalls_ht);
 298         if (ret < 0) {
 299                 goto error;
 300         }
 301
 302         for (i = 0; i < syscall_table_nb_entry; i++) {
 303                 struct syscall *ksyscall;
 304
 305                 /* Skip empty syscalls. */
 306                 if (*syscall_table[i].name == '\0') {
 307                         continue;
 308                 }
 309
 310                 ksyscall = lookup_syscall(syscalls_ht, syscall_table[i].name);
 311                 if (ksyscall) {
 312                         update_event_syscall_bitness(events, i, ksyscall->index);
 313                         continue;
 314                 }
 315
 316                 ret = add_syscall_to_ht(syscalls_ht, i, index);
 317                 if (ret < 0) {
 318                         goto error;
 319                 }
 320
 321                 /* Copy the event information in the event's array. */
 322                 strncpy(events[index].name, syscall_table[i].name,
 323                                 sizeof(events[index].name));
 324                 update_event_syscall_bitness(events, i, index);
 325                 events[index].type = LTTNG_EVENT_SYSCALL;
 326                 /* This makes the command line not print the enabled/disabled field. */
 327                 events[index].enabled = -1;
 328                 index++;
 329         }
 330
 331         destroy_syscall_ht(syscalls_ht);
 332         *_events = events;
 333         rcu_read_unlock();
 334         return index;
 335
 336 error:
 337         destroy_syscall_ht(syscalls_ht);
 338         free(events);
 339         rcu_read_unlock();
 340         return ret;
 341 }